in addition to that, this is per pete williams of nbc news. he now reports that the boston marathon bomber manhunt is now down to one person, the younger brother. initially, earlier today, there was some speculation that perhaps there was a third suspect. that is now being downplayed. and pete williams reports that the manhunt down to one person. in addition to that, the police officials are now telling pete williams that during the early morning watertown gun battle between police and the two brothers, about 200 rounds were exchanged. they have found seven ieds, improvised devices, that have been removed, in searches so far in watertown and also some from the house in cambridge. in addition to that, we have obtained these pictures from the owner of a shell station, which we're going to show you right now, and i want to explain the fact that, obviously, the younger brother is in the forefront, leaving the shell station there, but we've blacked out or blurred out the face of the second individual, because we don't know that the time stamp on th